Adhesive composite having distinct phases

ABSTRACT

A conformable adhesive article for use as a sterile medical dressing is described. The article includes a breathable polymeric matrix, a plurality of phases, and an adhesive composition positioned on the polymeric matrix. The plurality of phases preferably provide reinforcement and stiffness to the article. The article permits transport of moisture across the breathable polymeric matrix, preferably at an Inverted water moisture vapor transmission rate of at least 300 g/m 2 /24 hours.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.09/364,506, filed Jul. 30, 1999, now allowed.

FIELD OF THE INVENTION

The present invention is directed to conformable adhesive articles,including adhesive articles for use as sterile medical dressings. Theinvention is particularly directed to adhesive coated polymeric articleshaving high moisture vapor transmission rates. The articles of thepresent invention can be used for medical tapes, dressings, skinclosures, drapes, and for other uses where a breathable conformable filmis desired.

BACKGROUND OF THE INVENTION

Breathable films are widely used as protective layers over wounds,including dressings and surgical drapes. These films facilitate healingin a moist environment, act as a barrier to contamination frommicroorganisms, and allow for exchange of moisture to prevent excessivefluid buildup. Breathable films are preferably thin and flexible inorder to permit high moisture transmission rates and to conform well tovarious irregular surfaces of a patient's body. Films fitting thisdescription are available under a number of trade names, includingTEGADERM™ produced by Minnesota Mining and Manufacturing Company of St.Paul, Minn.; BIOCLUSIVE™ produced by Johnson & Johnson Company of NewBrunswick, N.J.; and OP-SITE™ produced by T. J. Smith & Nephew of Hull,England.

Unfortunately, the thin and flexible nature of breathable films canresult in challenges when applying them to patients. These challengesoften arise because dressings formed of adhesive coated film tend towrinkle and adhere to themselves, interfering with smooth, asepticapplication to a patient's skin. Various delivery systems have beenproposed to address this challenge. One such delivery system isdescribed in U.S. Pat. No. 5,531,855, which is directed to a releasableprotective liner that covers the adhesive coated surface of the film.Unfortunately, when the liner is removed, the adhesive coated film oftenstill wrinkles and adheres to itself.

An alternative delivery system includes a thin disposable frame on whichthe breathable film is releasably secured, such as the frames describedin U.S. Pat. No. 5,520,629. As the film is applied to a wound on apatient, the frame is lifted away, leaving the film adhered to thepatient. In such implementations, the film adheres more strongly to thepatient than it does to the frame, thereby allowing for the release ofthe film from the frame. Although this method can work well, it posessome difficulty in making large breathable films, and can be difficultto produce.

Accordingly, a need exists for a thin, breathable film that can beapplied to a wound in an easy and efficient manner. The film shouldallow for escape of moisture while protecting the wound fromcontamination. Such film should preferably be efficient and costeffective to produce, as well as easy to apply.

SUMMARY OF THE INVENTION

The invention is directed to a conformable adhesive article. The articleis suitable for use as a sterile medical dressing, and includes abreathable polymeric matrix, a plurality of phases, and an adhesivecomposition positioned on or within at least a portion of the polymericmatrix. The breathable polymeric matrix allows for the escape ofmoisture across the adhesive article. The plurality of phases reinforcethe polymeric matrix, thereby making a stronger matrix and permittingthe matrix thickness to be minimized. The reinforcing phases canincrease the stiffness of the article as measured by hand conformabilityand F₁₀ modulus conformability. The phases can also provide an increasein tensile strength of the article in order to make it less fragileduring application and more durable after application.

A preferred use of the article is as an adhesive dressing applied overwounds. The dressing aids in the regulation of the amount of moisture incontact with the wound. In certain embodiments, the article maintains asufficiently moist environment to prevent the underlying wound fromdehydrating, without creating pools of liquid that can cause adhesivefailure. The article preferably exhibits a satisfactory moisture vaportransmission rate while retaining its structural integrity in moistenvironments. This combination of breathability and strength allows fora superior breathable film that promotes the quick recovery of injuries,such as burns to a patient's skin.

The article preferably has enough modulus or stiffness to allow easyapplication to a patient, but is conformable enough to readily adapt tothe shape of the covered area. In certain implementations, the articlecan be readily applied without the use of a release film, a retainerframe surrounding the article, or retainer handles at the ends of thearticle. However, the article can alternatively be used with thesedevices to aid in application to a patient.

The modulus of the article is preferably sufficient to aid inapplication, but not so great as to interfere with conformability to thepatient. The article preferably exhibits increased modulus and tensilestrength relative to existing breathable films suitable as wounddressings. The article typically has a conformability (Hand) of at leastabout 2 and less than about 10 in the direction parallel to the phases(in the cross-web direction when the phases are co-extruded in adown-web machine direction) and at least about 2 and less than 25 in thedirection perpendicular to the phases (in the machine direction when thephases are co-extruded in a down-web machine direction).

In implementations where the film will be applied to generally flatsurfaces, the film can have greater modulus than a film that would beapplied to an irregular surface. Similarly, in implementations where thefilm will be applied to irregular surfaces or curved surfaces, then thefilm is preferably more flexible. However, even when the film hasgreater flexibility, such modulus is still preferably great enough tolimit the amount of contact of the filming adhesive surface with itself.

The article should also typically have sufficient tensile strength tofunction as a satisfactory wound drape or dressing. In certainimplementations the article has a tensile strength of at least about 8N/cm width in the direction perpendicular to the phases (cross-webdirection); and at least about 8 N/cm width, and preferably at leastabout 16 N/cm width in the direction parallel to the phases (machinedirection). The tensile strength can vary depending upon the directionof the phases. The tensile strength is preferably more than 50 percentgreater in the machine direction than a breathable polymeric matrix ofthe same thickness that does not contain a plurality of phases.

In order to allow transport of moisture away from a wound, the articletypically has an inverted water moisture vapor transmission rate of atleast about 300 g/m²/24 hours, preferably an inverted water moisturevapor transmission rate of at least about 1500 g/m²/24 hours, and morepreferably an inverted water moisture vapor transmission rate of atleast about 4000 g/m²124 hours. The article typically has an uprightwater moisture vapor transmission rate of at least about 300 g/m²/24hours, preferably an upright water moisture vapor transmission rate ofat least about 600 g/m²/24 hours, and more preferably an upright watermoisture vapor transmission rate of at least about 1000 g/m²/24 hours.

The breathable polymeric matrix can be formed of various materials. Thematrix may include an elastomeric material and the plurality of phasescan include a substantially non-elastic material. Alternatively, thebreathable polymeric matrix and the plurality of phases can be formed ofelastomeric materials, including a polymeric matrix comprising athermoplastic polyurethane. The matrix can contain one layer or morethan one layer, and the layers can comprise different materials or thesame material. In specific implementations, the plurality of phasesincludes phases that are continuous in one direction, but discontinuousin another direction. The phases can be formed of a polymeric materialdifferent from the material used to form the polymeric matrix. Thephases can have a significantly greater stiffness than the polymericmatrix and impart overall stiffness to the article by reinforcing thepolymeric matrix. The phases preferably provide support and stiffness tothe matrix without significantly reducing the conformability of thearticle.

In a specific implementation of the invention, the article comprises anextruded web containing a plurality of uniform, distinct phasespositioned proximate the web. The phases are discontinuous in across-web direction. The phases positioned proximate the web may beentirely within the web, partially within the web, or adhered to theexterior of the web. The embedded phases preferably have a width uniformto within a coefficient of variation of less than 8 percent for threeconsecutive discontinuous phases. The width of these phases is measuredin a cross-section of the web cut transverse (i.e., cross-web) to themachine direction (i.e., down-web) and is the largest dimension of thecross-section of the phases in the cross-web direction.

In certain implementations, the article is made into a roll good thatfacilitates easy dispensing of the breathable film. The roll goodincludes a breathable polymeric matrix having a first surface and asecond surface, a plurality of substantially continuous phases retainedproximate the polymeric matrix, and an adhesive composition positionedon at least a portion of the first surface of the polymeric matrix. Theroll good can include perforations to form individual lengths of sterilemedical dressings. These perforations provide tear lines that facilitatetearing of the roll good into shorter lengths.

The phases can be formed of a material compatible with the matrix toform a substantially integrated product with a strong interface betweenthe matrix and the phases. Alternatively, incompatible materials can beco-extruded to form the article. In such implementations, the phases arepreferably encapsulated within the matrix in order to secure the phasesin place. As used herein, “compatible” refers to the property of forminga strong interface between the two materials, while “incompatible”materials form a weak interface. Thus, one implementation of theinvention provides for a plurality of phases substantially surrounded bythe polymeric matrix and compatible with the matrix, and a secondimplementation provides for phases substantially surrounded by thepolymeric matrix and not substantially compatible with the polymericmatrix.

Numerous alternative processes can be used to form the articles of theinvention. These processes can alter the properties of the finishedarticle, as well as the structure of the article. For example, theplurality of phases can be retained on the same surface of the polymermatrix as the adhesive composition, or can be retained on an oppositesurface from the adhesive composition. When the plurality of phases areretained on the same surface as the adhesive composition, the phases canbe intermediate the adhesive composition and the surface of thepolymeric matrix or can be placed on top of the adhesive composition.The plurality of phases can be heat laminated between a polymeric matrixhaving at least two layers, extruded in two stages, solvent cast onto arelease sheet, etc. A specific process suitable for forming thebreathable article includes providing an extrudable material and anextrusion die, as described in United States patent application AttorneyDocket No. 54324USA4A entitled “Polymeric Articles Having EmbeddedPhases, filed on Jul. 30, 1999.

Other features and advantages of the invention will be apparent from thefollowing description of the preferred embodiments thereof, and from theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a medical dressing containing abreathable film constructed and arranged in accordance with theinvention.

FIG. 1B is a fractional cross-sectional view of the medical dressingshown in FIG. 1A taken along plane A-A′.

FIG. 2A is a fractional cross-sectional view of a conformable adhesivearticle constructed and arranged in accordance with the invention,showing a polymeric matrix surrounding a plurality of phases.

FIG. 2B is a fractional cross-sectional view of a conformable adhesivearticle constructed and arranged in accordance with the invention,showing a polymeric matrix with a plurality of phases adhered to asurface of the matrix.

FIG. 2C is a fractional cross-sectional view of a conformable adhesivearticle constructed and arranged in accordance with the invention,showing an alternate implementation of a polymeric matrix with aplurality of phases adhered to a surface of the matrix.

FIG. 2D is a fractional cross-sectional view of a conformable adhesivearticle constructed and arranged in accordance with the invention,showing a matrix having two layers.

FIG. 3A is a perspective view of an extrusion die constructed inaccordance with an embodiment of the invention.

FIG. 3B is a perspective view of an extrusion die vane constructed inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to a conformable adhesive article for use as asterile medical dressing. The article includes a breathable polymericmatrix, a plurality of phases proximate the matrix, and an adhesivecomposition positioned on at least a portion the polymeric matrix. Thebreathable polymeric matrix allows for escape of moisture across theadhesive article. This escape of moisture is particularly advantageouswhen the article is used as a medical dressing, drape, or otherbreathable article.

The plurality of phases reinforce the polymeric matrix, therebystrengthening the matrix and permitting the thickness of the matrix tobe reduced. The reinforcement can also increase the modulus of thearticle so as to make it easier to apply to a patient, with reducedproblems associated with adhesion of the article to itself. The phasescan also provide an increase in tensile strength of the article in orderto make it more durable. The modulus of the article is preferably not sogreat as to interfere with conformability to the patient. The articletypically has a conformability (Hand) of at least about 2, and less than10 in the direction parallel to the phases (measured such that the baris parallel to the phases) and at least about 2 and less than 25 thedirection perpendicular to the phases (measured such that the bar isperpendicular to the phases). The article preferably has aconformability (hand) of less than 5 in the direction parallel to thephases and less than 10 in the direction perpendicular to the phases.

A preferred use of the article is as an adhesive dressing forapplication over wounds. The dressing effectively regulates the amountof moisture in contact with the wound underlying the dressing. Incertain embodiments, the article maintains a sufficiently moistenvironment to prevent the underlying wound from dehydrating, withoutcreating pools of liquid that can cause adhesive failure. The articleexhibits a high moisture vapor transmission rate while retaining itsstructural integrity in moist environments. The existence of phases of asecond material within the matrix can promote formation of a strongerarticle than would otherwise be obtained without use of phases. Inaddition, the phases are preferably constructed and arranged such thatmoisture transport through the matrix is not greatly reduced.

In a preferred implementation, the article is stiff enough to allow easyapplication to a patient, but conformable enough to readily adapt to theshape of the covered area. The article can be readily applied to apatient without the use of a release film, a retainer frame surroundingthe article, or retainer handles at the ends of the article.

The article should have sufficient tensile strength to function as asatisfactory wound drape or dressing. In certain implementations thearticle has a tensile strength of at least about 8 N/cm width in thedirection perpendicular to the phases (cross-web direction when thematrix and phases are co-extruded); and at least about 8 N/cm width, andpreferably at least about 16 N/cm width in the direction parallel to thephases (machine direction when the matrix and phases are co-extruded).The tensile strength can vary depending upon the direction of thephases, and the tensile strength is preferably more than 50 percentgreater than a breathable polymeric matrix of the same thickness thatdoes not contain a plurality of phases.

In order to allow transport of moisture away from a wound, the articletypically has an inverted water moisture vapor transmission rate of atleast about 300 g/m²/24 hours, preferably an inverted water moisturevapor transmission rate of at least about 1500 g/m²/24 hours, morepreferably an inverted water moisture vapor transmission rate of atleast about 4000 g/m²/24 hours. The article typically has an uprightwater moisture vapor transmission rate of at least about 300 g/m²/24hours, preferably an upright water moisture vapor transmission rate ofat least about 600 g/m²/24 hours, more preferably an upright watermoisture vapor transmission rate of at least about 1000 g/m²/24 hours.

The article is preferably conformable to anatomical surfaces so thatwhen the article is applied to a human or animal anatomical surface itconforms to the surface even when the surface is moved. Preferredarticles are also conformable to animal or human anatomical joints. Whenthe joint is flexed and then returned to its unflexed position, thearticle stretches to accommodate the flexing of the joint but isresilient enough to continue to conform to the joint when the joint isreturned to its unflexed position. Generally the films are from 12 to 25microns thick. Conformability is somewhat dependent upon thickness, thusthe thinner the film the more conformable it is.

A measure of conformability is the F₁₀ modulus. The F₁₀ modulus shouldpreferably be greater than about 1.8 N/cm and more preferably greaterthan about 1.4 N/cm. In preferred embodiments the wound dressings anddrapes, films having an F₁₀ modulus upwards of 4.4 N/cm may be used. TheF₁₀ modulus increases the conformability decreases and the ability ofthe film to perform comfortably as medical dressings decreases.

In reference now to the figures, an example breathable polymeric wounddressing 10 constructed in accordance with the invention is shown inperspective view in FIG. 1A. Wound dressing 10 includes a top surface12, a bottom surface 14, first and second ends 16, 18, and edges 20, 22.Wound dressing 10 is constructed of a thin polymeric matrix that allowsfor release of moisture from bottom surface 14 to top surface 12. Anadhesive 23 is positioned on the bottom surface 14, and also allows forrelease of moisture through the dressing 10.

In the implementation shown the adhesive is placed over only a portionof bottom surface 14, such as by the method taught in U.S. Pat. No.4,798,201. In other implementations (shown later in FIG. 2A-2D), theadhesive covers all or substantially all of bottom surface 14. When theadhesive covers substantially all of the bottom surface, then theadhesive itself should be breathable. However, when the adhesive coverssignificantly less than all of bottom surface 14, then the adhesive isoptionally either breathable or not breathable.

A cross-sectional fragment 24 of wound dressing 10, taken along planeA-A′, is depicted in FIG. 1B. Fragment 24 of dressing 10 includes aplurality of phases 26 positioned within matrix 28. In the embodimentshown, matrix 28 contains a single layer into which the plurality ofphases 26 are positioned. Phases 26 can be formed within matrix 28 by,for example, coextruding the phases 26 and matrix 28 at the same time.In the embodiment depicted in FIGS. 1A and 1B, the phases are continuousbetween the ends 16 and 18 of the dressing 10, but are discontinuousfrom edge 20 to edge 22.

FIGS. 2A through 2D show additional cross-sectional fragments ofarticles constructed in accordance with the invention. In FIG. 2A,fragment 30 includes a plurality of phases 32 entirely surrounded bymatrix 34. An adhesive 36 is applied to the bottom surface 38 offragment 30. In contrast, FIG. 2B shows fragment 40 with a plurality ofphases 42 secured to an upper surface 44 of the matrix 46. An adhesive48 is positioned on the bottom surface 50 of fragment 40. Yet anotherembodiment is shown in FIG. 2C, which depicts a fragment 52 with aplurality of phases 54 secured to the bottom surface 56 of the matrix 58by adhesive 60. A further embodiment is shown in FIG. 2D, depictingfragment 62 with a matrix having an upper layer 64 and a lower layer 66.The phases 68 are positioned within the matrix between layers 64, 66.

In a specific implementation of the invention, the article includes anextruded breathable film and a plurality of distinct, co-extruded phasespositioned proximate the film. The article is extruded as a continuousor substantially continuous web, with the phases discontinuous in across-web direction. The phases positioned proximate the film may beentirely within the film, partially within the film, or adhered to theexterior of the film. The extruded phases preferably have a widthuniform to within a coefficient of variation of less than 8 percent forthree consecutive discontinuous phases. The width of these extrudedphases is measured in a cross-section of the film cut transverse (i.e.,cross-web) to the machine direction (i.e., down-web) and is the largestdimension of the cross-section of the phases in the cross-web direction.In one embodiment, the phases are spaced at substantially uniformintervals in the cross-web direction.

The article can be made into a roll good that facilitates easydispensing. The roll good includes a breathable polymeric matrix havinga first surface and a second surface, a plurality of substantiallycontinuous phases retained proximate the polymeric matrix, and anadhesive composition positioned on at least a portion of the firstsurface of the polymeric matrix. The roll good can include perforationsto form individual lengths of sterile medical dressings.

The invention is further directed to processes for making a breathablepolymeric co-extruded article. The phases can be co-extruded with thepolymeric matrix, thereby forming a substantially integrated productwith a strong interface between the matrix and the phases.Alternatively, incompatible materials can be co-extruded to form thearticle. In such implementations, the phases are preferably encapsulatedwithin the matrix in order to secure the phases in place. Thus, theplurality of phases can be substantially surrounded by the polymericmatrix and have a strong interface with the matrix, or can besubstantially surrounded by the polymeric matrix and not have a stronginterface with the polymeric matrix.

Numerous alternative processes can be used for forming the articles ofthe invention. These processes can alter the properties of the finishedproduct, as well as the structure of the product. For example, theplurality of phases can be retained on the same surface of the polymermatrix as the adhesive composition, or can be retained on an oppositesurface. When the plurality of phases are retained on the same surfaceas the adhesive composition, the phases can be intermediate the adhesivecomposition and the surface of the polymeric matrix. The plurality ofphases can be heat laminated between a polymeric matrix having at leasttwo layers, extruded in two stages, solvent cast onto a release sheet,etc.

When the breathable polymeric article is made by co-extrusion in otherimplementations, two extruders provide molten streams of first andsecond extrudable materials. The extrudable materials are extruded fromthe die such that the first extrudable material substantially surroundsor forms a matrix around the second extrudable material, which becomesphases embedded within the matrix. Alternatively, a third extruder maybe used to feed a third material into the die to form a matrix having adifferent material for each matrix layer.

A specific process suitable for forming the breathable article includesproviding an extrudable material and an extrusion die, as described inU.S. Pat. No. 6,447,875. In a specific embodiment, the die contains twochambers and an adjustable vane between the chambers. The vane containsa cavity having at least one input orifice positioned to receiveextrudable material and at least one exit orifice. The cavity isdesigned so that the difference in pressure of molten polymer from oneend to the other is sufficiently small to yield embedded phases of gooduniformity extruded from the exit orifices. A matrix material isextruded through the chambers of the die, and a phase material isextruded through the exit orifice in the vane to produce a co-extrudedweb containing the matrix and phase materials. The phase material isembedded between the two layers of the first material.

In reference now to FIG. 3A, a perspective view of an extrusion die 70is depicted showing an exemplary apparatus that can be used to form abreathable polymeric article in accordance with the invention. The die70 depicted in FIG. 3A is one apparatus suitable for formation of thearticle of the invention, and other apparatuses are also appropriate forvarious implementations. Die 70 includes a body 72 that has at leastfirst and second orifices 74 and 76. Orifice 74 provides entry for afirst extrudable material, while orifice 76 provides entry for a secondextrudable material. Extrusion die 70 also includes an exit port 78. Thewidth of port 78 (also called the die gap) is typically 1000 μm or less.Extrudable materials enter die 70 at orifices 74 and 76, respectively,flow through die 70, and then leave die 70 at exit port 78 as aco-extruded web.

Within extrusion die 70 is an adjustable vane 80, shown in FIG. 3B.Adjustable vane 80 includes at least two orifices 82 and 84. Entranceorifice or orifices 82 allow entry of polymeric material for theinterior of vane 80, and outlet orifices 84 permit the exit of polymericmaterial from the interior of vane 80. The shape and position of outletorifices 84 define the shape and position of the plurality of distinctembedded phases in the polymeric web. Advantageously, tip 86 of vane 80may be removable and replaceable to allow placement of different tipshaving different configurations of orifices 84 to form different webconfigurations. Vane 80 is thus adjustable in at least one of two modes.The vane can be pivoted so the tip can be moved closer to the exit ofone die chamber or the other causing a difference in die gap for theexits of each of the two matrix layers. This can result in a differentmatrix layer thickness if each layer is made with matrix material havinga similar melt viscosity. Alternatively, different exit gaps can resultin a similar matrix layer thickness if each layer is made with matrixmaterial having a different melt viscosity. The vane can also beadjusted by replacement of tip 86 with one having orifices of differentshapes and spacing.

This implementation is advantageous in that materials are co-extruded ina controlled manner. The materials are brought together in the meltstate, thereby allowing for improved adhesion to one another. Inaddition, even when the materials are not compatible, they may still beco-extruded in order to produce a breathable polymeric article.

If one matrix material is less viscous than the other, it is possible tonarrow the gap through which the less viscous matrix material flows inorder to maintain uniformity of the thickness of each of the two matrixlayers. The gap can be altered during processing in order to account forvariations in processing conditions, such as changes in the temperature,pressure, flow rate, or viscosity over time. Thus, if die 70 has awarmer upper portion than lower portion resulting in lower viscosity ofmaterials flowing through the upper gap, then the gap can be adjusted toaccount for this change in viscosity. In addition, the gap can bealtered to achieve a different thickness in each matrix layer. This isparticularly useful when each matrix layer is of a different material,e.g., a thermoplastic elastomer and a pressure-sensitive adhesive, wheredifferent properties are desired from each layer of the matrix.

The co-extrusion process of the invention is able to reproduce in thephases the relative dimensions of the orifices in the tip to a degreethat has not previously been known. In one aspect, where the orificeshave substantially the same dimensions, the width of the discontinuousembedded phases are relatively uniform. The coefficient of variation(COV) of the width of any three consecutive discontinuous phases is lessthan 8, preferably less than 5 and more preferably less than 3 percentwhen three or more similarly sized orifices are used.

Another way of modifying the properties of the webs of the invention isto use specific materials having desired properties for the layers ofthe matrix and the embedded phases. Suitable polymeric materials forforming the matrix layers and embedded phases of the inventivecoextruded web include pressure sensitive adhesives, thermoplasticmaterials, elastomeric materials, polymer foams, high viscosity liquids,etc.

“Pressure-sensitive adhesives” (PSAs) include adhesives that displaypermanent and aggressive tackiness to a wide variety of substrates afterapplying only light pressure. PSAs have a four-fold balance of adhesion,cohesion, stretchiness, and elasticity, and are normally tacky at usetemperatures, which is typically room temperature (i.e., about 20° C. toabout 30° C.). PSAs also typically have an open time tack (i.e., periodof time during which the adhesive is tacky at room temperature) on theorder of days and often months or years. An accepted quantitativedescription of pressure-sensitive adhesives is given by the Dahlquistcriterion line (as described in Handbook of Pressure-Sensitive AdhesiveTechnology, Second Edition, D. Satas, ed., Van Nostrand Reinhold, NewYork, N.Y., 1989, pages 171-176), which indicates that materials havinga storage modulus (G′) of less than about 3×10⁵ Pascal (measured at 10radians/second at a temperature of about 20° C. to about 22° C.) havepressure-sensitive adhesive properties, but materials having a G′ inexcess of this value do not.

“Nonpressure-sensitive adhesives” include nontacky polymeric materialsas well as tacky polymeric materials that, when in the melt state, donot display pressure sensitive properties, or other materials that haveadhesive properties at room temperature but do not meet the Dahlquistcriterion as described above. Such materials have a storage modulus (G′)of at least about 3×10⁵ Pascal (measured at 10 radians/second at a roomtemperature of about 20° C. to about 22° C.). These materials can benontacky thermoplastic materials, which can be elastomeric ornon-elastomeric. Alternatively, they can be nontacky elastomers.

Preferred materials for use in preparing the articles of the presentinvention, whether they include pressure-sensitive adhesives ornonpressure-sensitive adhesives, are melt processable. That is, they arefluid or pumpable at the temperatures used to melt process the webs(e.g., about 50° C. to about 300° C.), and they form films. Furthermore,preferred materials do not significantly degrade or gel at thetemperatures employed during melt processing (e.g., extruding orcompounding). Preferably, such materials have a melt viscosity of about10 poise to about 1,000,000 poise, as measured by capillary meltrheometry at the processing temperatures and shear rates employed inextrusion. Typically, suitable materials possess a melt viscosity withinthis range at a temperature of about 175° C. and a shear rate of about100 seconds⁻¹.

Pressure-sensitive adhesives useful in articles of the present inventioncan be any material that has pressure-sensitive adhesive properties asdescribed above at use temperatures, which are typically about roomtemperature (i.e., about 20° C. to about 30° C.). Generally, althoughnot necessarily, particularly useful pressure-sensitive adhesives areamorphous with a glass transition temperature (Tg) of less than about20° C.

The pressure-sensitive adhesive material can include a singlepressure-sensitive adhesive, a mixture (e.g., blend) of severalpressure-sensitive adhesives, or a mixture (e.g., blend) of apressure-sensitive adhesive and a material that is anonpressure-sensitive adhesive (e.g., a nontacky thermoplastic material,which may or may not be elastomeric), as long as the layer haspressure-sensitive adhesive properties. Examples of somepressure-sensitive adhesive blends are described in PCT Publication Nos.WO 97/23577, 97/23249, and 96/25469. Similarly, a suitablenonpressure-sensitive adhesive matrix layer can include a singlematerial that is a nonpressure-sensitive adhesive, a mixture of severalsuch materials, or a mixture of a material that is not apressure-sensitive adhesive with a pressure-sensitive adhesive, as longas the layer does not have pressure-sensitive adhesive properties.

Pressure-sensitive adhesives useful in the present invention can beself-tacky or require the addition of a tackifier. Such materialsinclude, but are not limited to, tackified natural rubbers, tackifiedsynthetic rubbers, tackified styrene block copolymers, self-tacky ortackified acrylate or methacrylate copolymers, self-tacky or tackifiedpoly-α-olefins, and self-tacky or tackified silicones. Examples ofsuitable pressure-sensitive adhesives are described in U.S. Pat. No. Re24,906 (Ulrich), U.S. Pat. No. 4,833,179 (Young et al.), U.S. Pat. No.5,209,971 (Babu et al.), U.S. Pat. No. 2,736,721 (Dexter), and U.S. Pat.No. 5,461,134 (Leir et al.), for example. Others are described in theEncyclopedia of Polymer Science and Engineering, vol. 13,Wiley-Interscience Publishers, New York, 1988, and the Encyclopedia ofPolymer Science and Technology, vol. 1, Interscience Publishers, NewYork, 1964.

Useful natural rubber pressure-sensitive adhesives generally containmasticated natural rubber, one or more tackifying resins, and one ormore antioxidants. Useful synthetic rubber adhesives are generallyrubbery elastomers, which are either inherently tacky or nontacky andrequire tackifiers. Inherently tacky (i.e., self-tacky) synthetic rubberpressure-sensitive adhesives include for example, butyl rubber, acopolymer of isobutylene with less than 3 percent isoprene,polyisobutylene, homopolymers of isoprene, polybutadiene, orstyrene/butadiene rubber.

Styrene block copolymer pressure-sensitive adhesives generally compriseelastomers of the A-B or A-B-A type, wherein, in this context, Arepresents a thermoplastic polystyrene block and B represents a rubberyblock of polyisoprene, polybutadiene, or poly(ethylene/butylene), andtackifying resins. Examples of the various block copolymers useful inblock copolymer pressure-sensitive adhesives include linear, radial,star, and tapered block copolymers. Specific examples include copolymerssuch as those available under the trade designations Kraton from ShellChemical Co., Houston, Tex., and Europrene Sol from EniChem ElastomersAmericas, Inc., Houston, Tex. Examples of tackifying resins for use withsuch styrene block copolymers include aliphatic olefin-derived resins,rosin esters, hydrogenated hydrocarbons, polyterpenes, terpene phenolicresins derived from petroleum or turpentine sources, polyaromatics,coumarone-indene resins, and other resins derived from coal tar orpetroleum and having softening points above about 85° C.

(Meth)acrylate (i.e., acrylate and methacrylate or “acrylic”)pressure-sensitive adhesives generally have a glass transitiontemperature of about −20° C. or less and typically include an alkylester component such as, for example, isooctyl acrylate, 2-ethyl-hexylacrylate, and n-butyl acrylate, and a polar component such as, forexample, acrylic acid, methacrylic acid, ethylene vinyl acetate, andN-vinyl pyrrolidone. Preferably, acrylic pressure-sensitive adhesivescomprise about 80 wt-% to about 100 wt-% isooctyl acrylate and up toabout 20 wt-% acrylic acid. The acrylic pressure-sensitive adhesives maybe inherently tacky or tackified using a tackifier such as a rosinester, an aliphatic resin, or a terpene resin.

Poly-α-olefin pressure-sensitive adhesives, also called poly(1-alkene)pressure-sensitive adhesives, generally comprise either a substantiallyuncrosslinked polymer or an uncrosslinked polymer that may haveradiation activatable functional groups grafted thereon as described inU.S. Pat. No. 5,209,971 (Babu et al.). Useful poly-α-olefin polymersinclude, for example, C₃-C₁₈ poly(1-alkene) polymers. The poly-α-olefinpolymer may be inherently tacky and/or include one or more tackifyingmaterials such as resins derived by polymerization of C₅-C₉ unsaturatedhydrocarbon monomers, polyterpenes, synthetic polyterpenes, and thelike.

Silicone pressure-sensitive adhesives comprise two major components, apolymer or gum and a tackifying resin. The polymer is typically a highmolecular weight polydimethylsiloxane or polydimethyldiphenylsiloxanethat contains residual silanol functionality (SiOH) on the ends of thepolymer chain, or a block copolymer comprising polydiorganosiloxane softsegments and urea terminated hard segments. The tackifying resin isgenerally a three-dimensional silicate structure that is endcapped withtrimethylsiloxy groups (OSiMe₃) and also contains some residual silanolfunctionality. Silicone pressure-sensitive adhesives are described inU.S. Pat. No. 2,736,721 (Dexter). Silicone urea block copolymerpressure-sensitive adhesive are described in U.S. Pat. No. 5,461,134(Leir et al.), and PCT Publication Nos. WO 96/34029 and 96/35458.

Nonpressure-sensitive adhesive polymeric materials used in the articlesof the present invention include one or more thermoplastic materials,which may or may not be elastomeric materials, and elastomers. These maybe adhesive (i.e., tacky) when in the melt state or nonadhesive (i.e.,nontacky) materials, as long as the adhesive materials are not pressuresensitive, as defined above.

Thermoplastic materials are generally materials that flow when heatedsufficiently above their glass transition temperature and become solidwhen cooled. They may be elastomeric or non-elastomeric. Thermoplasticmaterials useful in the present invention that are generally considerednon-elastomeric include, for example, polyolefins such as isotacticpolypropylene, low density polyethylene, linear low densitypolyethylene, very low density polyethylene, medium densitypolyethylene, high density polyethylene, polybutylene, non-elastomericpolyolefin copolymers or terpolymers such as ethylene/propylenecopolymer and blends thereof; ethylene-vinyl acetate copolymers such asthose available under the trade designation Elvax from E.I. DuPont deNemours, Inc., Wilmington, Del.; ethylene acrylic acid copolymers;ethylene methacrylic acid copolymers such as those available under thetrade designation Surlyn 1702 from E.I. DuPont de Nemours, Inc.;polymethylmethacrylate; polystyrene; ethylene vinyl alcohol; polyestersincluding amorphous polyester; polyamides; fluorinated thermoplasticssuch as polyvinylidene fluoride and fluorinated ethylene/propylenecopolymers; halogenated thermoplastics such as chlorinated polyethylene;polyether-block-amides such as those available under the tradedesignation Pebax 5533 from Elf-Atochem North America, Inc.Philadelphia, Pa.

Thermoplastic materials that have elastomeric properties are typicallycalled thermoplastic elastomeric materials. Thermoplastic elastomericmaterials are generally defined as materials that exhibit highresilience and low creep as though they were covalently crosslinked atambient temperatures, yet process like thermoplastic non-elastomers andflow when heated above their softening point. Thermoplastic elastomericmaterials useful in the articles of the present invention include, forexample, linear, radial, star, and tapered block copolymers such asthose listed above with respect to pressure-sensitive adhesives (e.g.,styrene-isoprene block copolymers, styrene-(ethylene-butylene) blockcopolymers, styrene-(ethylene-propylene) block copolymers, andstyrene-butadiene block copolymers); polyetheresters such as thatavailable under the trade designation Hytrel G3548 from E.I. DuPont deNemours, Inc.; polyether block amides such as Pebax available fromAtochem, Philadelphia, Pa.; ethylene copolymers such as ethylene vinylacetates, ethylene/propylene copolymer elastomers orethylene/propylene/diene terpolymer elastomers and metallocenepolyolefins such as polyethylene, poly (1-hexene), copolymers ofethylene and 1-hexene, and poly(1-octene); thermoplastic elastomericpolyurethanes such as that available under the trade designationMorthane PE44-203 polyurethane from Morton International, Inc., Chicago,Ill. and the trade designation Estane 58237 polyurethane from B. F.Goodrich Company, Cleveland, Ohio; polyvinylethers; poly-α-olefin-basedthermoplastic elastomeric materials such as those represented by theformula —(CH₂CHR)_(x) where R is an alkyl group containing 2 to 10carbon atoms, and poly-α-olefins based on metallocene catalysis such asEngage EG8200, ethylene/poly-α-olefin copolymer available from DowPlastics Co., Midland, Mich.

Elastomers, as used herein, are distinct from thermoplastic elastomericmaterials in that the elastomers require crosslinking via chemicalreaction or irradiation to provide a crosslinked network, which impartsmodulus, tensile strength, and elastic recovery. Elastomers useful inthe present invention include, for example, natural rubbers such asCV-60, a controlled viscosity grade of rubber, and SMR-5, a ribbedsmoked sheet rubber; butyl rubbers, such as Exxon Butyl 268 availablefrom Exxon Chemical Co., Houston, Tex.; synthetic polyisoprenes such asCariflex, available from Shell Oil Co., Houston, Tex., and Natsyn 2210,available from Goodyear Tire and Rubber Co., Akron, Ohio;ethylene-propylenes; polybutadienes; polybutylenes; polyisobutylenessuch as Vistanex MM L-80, available from Exxon Chemical Co.; andstyrene-butadiene random copolymer rubbers such as Ameripol Synpol1011A, available from American Synpol Co., Port Neches, Tx.

Foams are those materials made by combining the above polymericmaterials with blowing agents. The resulting mixtures are then subjectedto various changes known in the art to activate the blowing agent usedto form a multiplicity of cells within the polymer. Additionalcrosslinking may occur to cause resulting foams to be more stable. Aparticularly useful foam, when an elastic foam matrix is desired, isthat disclosed in Ser. No. 09/325,963, Attorney Docket No. 54664USA4A,“Breathable Polymer Foams” filed Jun. 4, 1999 and incorporated herein byreference. High viscosity liquids are any that do not diffuse throughthe matrix material and prematurely escape the article of the invention.These include, for example, various silicone oils, mineral oils andspecialty materials having a sharp melting temperatures below roomtemperature.

Viscosity reducing polymers and plasticizers can also be blended withthe elastomers. These viscosity reducing polymers include thermoplasticsynthetic resins such as polystyrene, low molecular weight polyethyleneand polypropylene polymers and copolymers, or tackifying resins such asWingtack™ resin from Goodyear Tire & Rubber Company, Akron, Ohio.Examples of tackifiers include aliphatic or aromatic liquid tackifiers,aliphatic hydrocarbon resins, polyterpene resin tackifiers, andhydrogenated tackifying resins. Additives such as dyes, pigments,antioxidants, antistatic agents, bonding aids, antiblocking agents, slipagents, heat stabilizers, photostabilizers, foaming agents, glassbubbles, starch and metal salts for degradability or microfibers canalso be used in the elastomeric phase. Suitable antistatic aids includeethoxylated amines or quaternary amines such as those described, forexample, in U.S. Pat. No. 4,386,125 (Shiraki), which also describessuitable antiblocking agents, slip agents and lubricants. Softeningagents, tackifiers or lubricants are described, for example, in U.S.Pat. No. 4,813,947 (Korpman) and include coumarone-indene resins,terpene resins, hydrocarbon resins and the like. These agents can alsofunction as viscosity reducing aids. Conventional heat stabilizersinclude organic phosphates, trihydroxy butyrophenone or zinc salts ofalkyl dithiocarbonate.

Various additives may be incorporated into the phase(s) and/or thematrix to modify the properties of the finished article. For example,additives may be incorporated to improve the adhesion of the phases andthe matrix to one another. The article may also be laminated to afibrous web. Preferably, the fibrous web is a nonwoven web such as aconsolidated or bonded carded web, a meltblown web, a spunbond web, orthe like. The fibrous web alternatively is bonded or laminated to thematrix by adhesives, thermal bonding, extrusion, ultrasonic welding orthe like. Preferably, a co-extruded web can be directly extruded ontoone or more fibrous webs.

Short fibers or microfibers can be used to reinforce the distinct phasesor matrix layers for certain applications. These fibers includepolymeric fibers, mineral wool, glass fibers, carbon fibers, silicatefibers and the like. Further, certain particles can be used, includingcarbon and pigments. Glass bubbles or foaming agents may be used tolower the density of the matrix layer or embedded phases and can be usedto reduce cost by decreasing the content of an expensive material or theoverall weight of a specific article. Suitable glass bubbles aredescribed in U.S. Pat. Nos. 4,767,726 and 3,365,315. Blowing agents usedto generate foams in melt processable materials are known in the art andinclude azodicarbonamides such as SAFOAM RIC-50 sodium bicarbonate-basedchemical blowing agent. Fillers can also be used to some extent toreduce costs. Fillers, which can also function as antiblocking agents,include titanium dioxide and calcium carbonate.

A number of additional steps can optionally be performed. For example,the article may be uniaxially or biaxially oriented, either sequentiallyor simultaneously, can be cured (such as through heat, electromagneticradiation, etc.), can be embossed, laminated, or can be dusted withvarious tack-reducing agents.

Articles of the invention are suitable for use in various medicalarticles, such as wound dressings and tapes, surgical drapes, and woundclosure systems. In certain embodiments, distinct phases are formed inthe polymeric matrix in order to provide increased strength and improvedhandling without affecting the overall conformability, transparency orbreathability of the polymeric material. Preferred matrix materials foruse in constructing such medical articles include breathable polymerssuch as polyurethanes, polyesters (e.g., Hytrel™ 4056 resin from Dupont,Wilmington, Del.), and polyether block amides (e.g., made from Pebax™3533, Pebax™ MX-1657, and Pebax™MX-1074, all available from Elf Atochem,Philadelphia, Pa.). Also preferred are polyolefins, e.g., polyethyleneand polypropylene, when constructed in a manner to allow breathability,such as when co-extruded with oil to form a porous film. Combinations ofthese two types of preferred matrix materials could also be used.Preferred phase materials for use in constructing such medical articlesinclude polyamides, polyethylene, polypropylene, polyesters and styreneblock copolymers, such as Kraton™ block copolymers.

In one preferred embodiment, distinct phases of polyester (e.g., Eastar™6763 from Eastman Chemical Company, Kingsport, Tenn.) are formed in abreathable polyurethane web matrix (e.g., Estane™ 58237 from B. F.Goodrich Company, Cleveland, Ohio) to increase strength and aid in theability to handle and position the article in final sheet or tape form.This represents a significant improvement over current surgicaldressings formed of polyurethane that are difficult to handle becausethey are too flexible and thus do not easily maintain a shape. Theaddition of phases to the polyurethane matrix allows for retention ofbreathability (at least about 300 grams/square meter/24 hours, andpreferably at least about 600 grams/square meter/24 hours by MoistureVapor Transmission Rate—Upright Method) while increasing tensilestrength and web handling characteristics. The down-web tensile strengthof the resulting webs typically is increased at least 50 percent overcomparable webs not having discontinuous phases and preferably isincreased at least 100 percent.

Alternate methods of making the above breathable article are laminationand other extrusion methods. One method of making the article bylamination involves placing a plurality of synthetic or natural fibersin a parallel direction between two sheets of breathable elasticmaterial. The resulting sandwich can be pressed together under heat bymeans of a platten press of a hot nip. An alternate extrusion method isthat disclosed in Krueger et al, U.S. Pat. No. 5,429,856, except the twomatrix layers are of an elastic breathable material and thediscontinuous phases include preferably inelastic thermoplasticmaterials.

The precise extruders employed in the inventive process are not criticalas any device able to convey melt streams to a die of the invention issatisfactory. However, it is understood that the design of the extruderscrew will influence the capacity of the extruder to provide goodpolymer melt quality, temperature uniformity, and throughput. A numberof useful extruders are known and include single and twin screwextruders. These extruders are available from a variety of vendorsincluding Davis-Standard Extruders, Inc. (Pawcatuck, Conn.), BlackClawson Co. (Fulton, N.Y.), Berstorff Corp (North Carolina), FarrelCorp. (Conn.), Moriyama Mfg. Works, Ltd. (Osaka, Japan). Other apparatuscapable of pumping organic melts may be employed instead of extruders todeliver the molten streams to the forming die of the invention. Theyinclude drum unloaders, bulk melters and gear pumps. These are availablefrom a variety of vendors, including Graco LTI (Monterey, Calif.),Nordson (Westlake, Calif.), Industrial Machine Manufacturing (Richmond,Va.), Zenith Pumps Div., Parker Hannifin Corp., (North Carolina).

Once the molten streams have exited the pump, they are typicallytransported to the die through transfer tubing and/or hoses. It ispreferable to minimize the residence time in the tubing to avoidproblems of, for example, melt temperature variation. This can beaccomplished by a variety of techniques, including minimizing the lengthof the tubing, providing appropriate temperature control of the tubing,and utilizing static mixers in the tubing to maintain a homogeneoustemperature in the tubing. Patterned tools which contact the web canprovide surface texture or structure to improve the ability to tear theweb in the cross web or transverse direction without affecting theoverall tensile strength or other physical properties of the product.

EXAMPLES

The invention is further illustrated by the following examples, whichare not intended to limit the scope of the invention. In the examples,all parts, ratios and percentages are by weight unless otherwiseindicated. The following test methods were used to characterize thearticles in the following examples:

Test Methods

Tensile Strength and Elongation

Tensile strength and elongation in the down-web direction of co-extrudedarticles were determined in the following manner. A 10.2 cm long by 2.5cm wide sample was placed between the jaws of an Instron™ Tensile Testerto expose a 5.1 cm gauge length. The crosshead and chart speeds were setat 25.4 cm/min. The jaws were drawn apart at 25.4 cm/min until themachine detected a break. Tensile strength and percent elongation werecalculated by the Instron™ software. Tensile strength measurements (eachwith 3 replications) were taken on samples oriented in the cross webdirection (with force of pull perpendicular to the orientation of thephases) and in the machine direction (with machine force of pullparallel to the orientation of the phases).

Moisture Vapor Transmission Rate (MVTR)

Moisture vapor transmission rates of the samples were tested usingeither the upright method (A) or inverted method (B) as described below.

A—Upright Method: Glass bottles were filled with approximately 50 ml ofwater. Three test samples and three control samples were cut into 3.8 cmdiameter samples using a round die cutter. The samples were placedbetween two foil rings that had holes cut in the centers. A rubbergasket was placed between the bottom of the foil and the glasscontainer. A screw cap with a 3.8 cm diameter hole was attached to theglass jar enclosing the foil-sample sandwich and gasket to the glass.The samples were conditioned for four hours at 40° C. at 20% relativehumidity in a control chamber. The cap was then tightly secured to thejar and the jar was removed from the chamber and weighed on ananalytical balance to the nearest 0.01 gram. The jars were returned tothe chamber for at least 18 hrs. (at the conditions listed above). Thebottles were then removed and weighed immediately to the nearest 0.01gram. Moisture vapor rates were calculated by the change in weightmultiplied by the exposed area divided by the time they were exposed.Rates are reported in grams per square meter in 24 hours.

B—Inverted Method: The same procedure was followed as outlined above.However, after the samples were conditioned and weighed, they werereturned to the chamber and the bottles were inverted so that the watercontacted the test surface. The bottles were left undisturbed for atleast 18 hrs. The bottles were then removed and weighed, and themoisture vapor transmission rate was calculated as above.

Conformability (Hand)

The total Hand conformability in grams of example sheet materials ortapes provides a measure of the drape/conformability of these materials.Those materials with a relatively high Hand value are stiff andnonconformable. Conversely, relatively low Hand values reflect soft,conformable materials. The Hand values reported for the followingexamples were obtained on a Thwing-Albert Handle-O-Meter Model No.211-300 (Thwing-Albert Instrument Co., Philadelphia, Pa.), according tothe procedures outlined in the instruction manual included with ModelNo. 211-300. All of the Hand measurements were performed on about 10 cmsquare sheet materials that were powdered with talc to reduce friction.Hand measurements (each with 3 replications) were taken on samplesoriented in the cross-web direction (with machine bar parallel to theorientation of the phases) and in the machine direction (with machinebar perpendicular to the orientation of the distinct phases).

Conformability (Modulus)

F₁₀ modulus as referred to herein is a measure of the force to elongatea sample 10 percent and is effectively determined using an Instron UnitModel 1102 from Instron Corp., 2500 Washington Street, Canton, Mass. Thecross-head speed of the Instron was set at ten inches per minute and thechart speed is set at ten inches (25.4 cm) per minute. The gauge lengthis set at two inches (5 cm) with the test sample cut to test a one-inchwidth (2.54 cm).

Modulus measurements (each with 3 replications) were taken on samplesoriented in the cross-web direction (with machine bar parallel to theorientation of the phases) and in the machine direction (with machinebar perpendicular to the orientation of the distinct phases).

Examples 1 and 2

Examples 1 and 2 describe the preparation of extruded articles having anelastic continuous polyurethane matrix and a plurality of distinctinelastic phases. The inelastic phases comprised either modifiedpolyester (Example 1) or polyethylene (Example 2).

For Example 1, a continuous extrusion was carried out using a 45 cm (18in) wide Cloeren™ two-layer multi-manifold die (available as Model96-1502 from Cloeren Co., Orange, Tex.) that had been modified asdescribed in U.S. Pat. No. 6,447,875. A vane tip containing 95 orificeswas mounted to the vane manifold with socket head bolts. The vane tiphad circular orifices each having a diameter of 508 microns (20 mils)and separated by a space of 4.1 mm (0.160 in) and extended from the vanetip 2.5 mm (0.100 in) into the matrix flow.

The continuous matrix material was an elastic material, Estane™ 58237polyurethane (B.F. Goodrich, Cleveland, Ohio). It was fed with a 51 mm(2.0-inch) Berlyn™ single screw extruder that was operated at atemperature profile of zone 1—149° C. (300° F.), zone 2—171° C. (340°F.) and zones 3 to 7—204° C. (400° F.). The 51 mm extruder was run at 25rpm with a head pressure of 31.1 MPa (4500 psi) to feed continuousmatrix material. The discontinuous phase material was an inelasticthermoplastic polymer, Eastar™ 6763 glycol modified polyester (EastmanChemical Co., Kingsport, Tenn.). It was fed with a 32 mm (1.25-inch)Killion™ single screw extruder (available from Davis-Standard KillionSystems, Cedar Grove, N.J.) that was operated with a temperature profileof zone 1—188° C. (370° F.), zone 2—227° C. (440° F.) and zones 3 and4—243° C. (470° F.). The 32 mm extruder was run at 6 rpm with a headpressure of 15.9 MPa (2300 psi) to feed discontinuous phase materialthrough the modified vane in the die. The die was operated at 218° C.(425° F.). The extrudate comprising a two-layer polymer matrixcontaining embedded discontinuous phases running down-web was extrudedinto a nip formed by a chrome casting wheel, at 7.2° C. (45° F.) and asilicone coated nip roll, at 7.2° C. (45° F.). The web take-away speedwas 11.3 m/min (37 fpm) resulting in an overall thickness of 43 microns(1.7 mils). The cast web was not oriented.

Example 2 was made as Example 1 except the discontinuous phase materialwas different and some conditions were changed. The temperature profilefor the extruder that fed the continuous matrix material was zone 1—149°C. (300° F.), zone 2—166° C. (330° F.) and zones 3 to 7—199° C. (390°F.). The 51 mm extruder was run at 10 rpm with a head pressure of 13.8MPa (2000 psi) to feed continuous matrix material. The discontinuousphase material was an inelastic thermoplastic polymer, Dowlex™ 10462Npolyethylene. The temperature profile of the extruder that fed thismaterial was zone 1—182° C. (360° F.), zone 2—241° C. (465° F.) andzones 3 and 4—249° C. (480° F.). The 32 mm extruder was operated at 12rpm with a head pressure of 3.5 MPa (500 psi) to feed discontinuousphase material. The temperature of the nip rolls was approximately 16°C. (60° F.). The material take-away speed was 5.2 m/min (17 fpm)resulting in an overall thickness of 79 microns (3.1 mils).

Example 3

Example 3 describes the preparation of an extruded adhesive articlehaving two layers of different materials (polyacrylate PSA andpolyurethane) that comprise an elastic continuous polymeric matrix and aplurality of distinct inelastic phases comprised of modified polyester.

An acrylic PSA (96 weight percent isooctyl acrylate/4 weight percentmethacrylic acid, water suspension polymerized), prepared according toU.S. Pat. No. 4,833,179 (Young) was dried to about 90 weight percent andmelt blended with Floral™ 85 (a tackifying resin available from HerculesInc., Wilmington, Del.) in a weight ratio of acrylate to Foral™ of80:20. The PSA was designated as PSA A.

Example 3 was made in a manner similar to Example 1 except that the twolayers of continuous matrix material were made of different materialsand an additional extruder was used. The first layer of continuousmatrix material was made of a tacky elastomeric material, PSA A, and thesecond layer was made of the elastic thermoplastic polymer, Estane™58237 polyurethane. The first continuous matrix material was fed with afirst extruder, a 34 mm fully intermeshing, co-rotating Leistritz™ twinscrew extruder that used an increasing temperature profile reaching apeak temperature of 193° C. (380° F.). The 34 mm extruder was run at 180rpm with gear pump speed of 4.7 rpm and a head pressure of 4.2 MPa (610psi) to feed continuous matrix material into the first feed orifice ofthe die. The second material was fed with the 51 mm extruder into thesecond feed orifice of the die.

The resulting construction, which comprised an article having a PSA onone side, a polyurethane on the opposite side, and a distinct phase ofpolyester embedded strands, provides an example of a polymeric matrixcomposed of two different materials.

Example 4

Example 4 describes the preparation of a laminated adhesive articlecomprising a first layer of extruded elastic polyurethane film, aplurality of nylon monofilaments, a second layer of extruded elasticpolyurethane film, and a polyacrylate PSA layer.

Twenty-five grams per square meter of a pressure sensitive adhesiveprepared in accordance with U.S. Pat. No. Re. 24,906, comprising acopolymer of 96% units of isooctyl acrylate and 4% units acrylamide wasapplied to a 80 pound (36 kg) bleached release liner, one side coated,silicone paper (1-80BKG-157) (DCP-Loyha, Willowbrook, Ill.) using astandard horizontal knife coater.

A 0.6 mil (14 micron) film of ESTANE 58309 polyurethane resin (B. F.Goodrich, Cleveland, Ohio) was extruded using conventional methods. Asilicone liner was placed on the bed of a fixture with a first layer offilm. A 4 pound (1.8 kg) test Nylon Monofilament fishing line (Berkley &Co. Inc., Spirit Lake, Iowa) was threaded in a parallel manner over thefirst layer of film (2 mm apart) using the ends of the fixture and asecond layer of film was place over the monofilaments with a secondrelease liner placed over the sandwich laminate. The laminate was thenplaced in a heated press at 190° C. and 2 tons (1800 kg) of pressure.The laminate was then laminated to the adhesive surface to form anadhesive article of the present invention.

Example 5

Example 5 describes the preparation of an extruded article (fromExample 1) coated with a microsphere-containing polyacrylate PSA.

A pressure sensitive adhesive matrix blended with polymeric microsphereswas prepared and coated on one surface of the Example 1 extruded articleaccording to the procedure described in Example 1 of Heinecke et al.,U.S. Pat. No. 5,849,325 to provide an adhesive article of the presentinvention.

Example 6

Example 6 describes the preparation of an extruded article (fromExample 1) pattern coated with a polyacrylate PSA.

The polyacrylate PSA described in Example 4 was pattern coated on onesurface of the Example 1 extruded article to form a 25 percent void areagrid according to the procedure described by Rawlings in U.S. Pat. No.4,798,201.

Example 7

Example 7 describes the preparation of an extruded article having anelastic continuous polyurethane matrix and a plurality of distinctelastic phases comprised of ultra low density polyethylene.

The continuous extrusion was carried out using a 45 cm wide Cloeren™three-layer multi-manifold die that had been modified as described inU.S. Pat. No. 5,429,856 (Krueger). A “comb” insert was bolted to theinternal surface of one of the two unmodified vanes and snugly engagedwith the second vane to allow the vanes to rotate in unison. The “comb”insert had orifices of 1.6 mm in length and a separation distance of 3.2mm.

The continuous matrix material was an elastic material, Estane™ 58309polyurethane. The matrix material was fed with a 63.5 mm Davis Standard™single screw (available from Davis-Standard Corp., Pawcatuck, Conn.)that operated at a temperature profile of zone 1—149° C. (300° F.), zone2—149° C. (300° F.), zone 3—177° C. (350° F.), zone 4—182° C. (360° F.),zone 5-6—188° C. (370° F.). The 63.5 mm extruder was run at 12 rpm tofeed the continuous matrix material. The discontinuous phase materialwas an elastic thermoplastic polymer, Engage™ 8200 (ultra low densitypolyethylene, Dupont, Wilmongton, Del.). It was fed with 19 mm Killion™single screw extruder (available from Davis-Standard Killion Systems,Cedar Grove, N.J.) that was operated with a temperature profile of zone1—155° C. (311° F.), zone 2—180° C. (356° F.), zones 3-4—200° C. (392°F.), and zone 5—210° C. (410° F.). The 19 mm extruder was run at 87.5rpm to feed the discontinuous phase material through the modified vaneand cutouts in the die. The die was operated at 204° C. (400° F.). Theextrudate comprising a two-layer polymer matrix containing embeddeddiscontinuous phases running down-web was extruded into a nip formed bya chrome casting wheel and a silicone coated nip roll. The materialtake-away speed was 15.2 m/min (50 fpm) resulting in an overall basisweight of 3.0 g/cm².

Example 8

Example 8 describes the preparation of a laminated adhesive articlecomprising a layer of polyacrylate PSA, a layer of extruded elasticpolyether block amide matrix and a plurality of distinct elastic phasescomprised of polyether block amide blended with linear low densitypolyethylene and a white pigment.

A 13 micron (0.5 mil) film of Pebax 3533 polyether block amide resin(Elf Atochem, Philadelphia, Pa.) was extruded using a 19 mm Rheocord™System 40 single screw extruded (Haake Buechler, Saddle Brook, N.J.)that was equipped with an Ultraflex 40 flex lip die (Extrusion Die Inc.,Chippewa Falls, Wis.). The extruder was operated with a temperatureprofile of zone 1—177° C. (350° F.), zone 2—182° C. (360° F.), zone3—193° C. (380° F.), and a die temperature of 204° C. (400° F.). Theextruder was run at 35 rpm. The extruded film was laminated to a layerof the polyacrylate PSA (on silicone release liner) described in Example4 using conventional laboratory lamination conditions.

The Ultraflex™ 40 die used above was then shimmed with 10 mil brass shimstock cut into 10 mm lengths to form a series of 5 apertures spaced 15mm apart. A blended thermoplastic polymer was prepared by combining 50%Pebax™ 3533 and 50% LLDPE 7047 (Union Carbide), and then adding 3% whitepigment concentrate CBE 101 E White (Charles B. Edwards & Co., Inc.).The blended polymer was fed into the shimmed Ultraflex 40 die using the19 mm Rheocord System 40 extruder described above that was operated witha temperature profile of zone 1—177° C. (350° F.), zone 2—188° C. (370°F.), and zones 3-4—199° C. (390° F.). The extruder was run at 10 rpm.The extruded discontinuous phase material was laminated to the Pebax™film layer of the above laminate using the same conventional laboratorylamination conditions.

Example 9

Example 9 describes the preparation of an adhesive article having anextruded elastic continuous matrix comprised of porous polypropylene anda plurality of distinct inelastic polypropylene phases, and a layer ofpolyacrylate PSA.

Example 9 was made in a manner similar to Example 1 except thecontinuous matrix material was made of a melt blend of 40% by weightmineral oil and 60% by weight thermoplastic polymer, a dry blend of 95%SD45 polypropylene (Union Carbide, Danbury, Conn.) and 5% of a 2% Millad3905 (Milliken Chemical, Inman, S.C.) nucleating agent concentrate. TheMillad 3905 amounted to 0.1% of the total continuous matrix. Thecontinuous matrix material was fed with a 34 mm fully intermeshing,co-rotating Leistritz™ twin screw extruder that used an increasingtemperature profile reaching a peak temperature of 232° C. (450° F.).The discontinuous phase material was an inelastic thermoplastic polymer,PP 3374 polypropylene (Fina Oil & Chemical Co., Dallas, Tex.). A 32 mm(1.25-inch) Killion™ single screw extruder was operated with atemperature profile of zone 1—182° C. (360° F.), zone 2—221° C. (430°F.), and zones 3 and 4—243° C. (470° F.). The 32 mm extruder was run at20 rpm with a head pressure of 15.9 mPa (2300 psi). The construction wasthen length oriented and tentered by a factor of 2.0 in both directionsto provide porosity. The oriented temperature was 65° C. A detaileddescription of preparing porous films can be found in Shipman, U.S. Pat.No. 4,536,256.

The extruded film was laminated to a layer of polyacrylate PSA (on asilicone release liner) described in Example 4 using conventionallaboratory lamination conditions.

Evaluations

Samples of articles from Examples 1, 3 and 9 were evaluated forstiffness (Hand and F₁₀ modulus measurements), tensile strength atbreak, percent elongation at break, and MVTR (upright method). Theresults are provided in Table 1 and are compared with comparative datafrom the commercial adhesive dressings TEGADERM™ HP (3M Company) andOP-SITE™ IV (Smith & Nephew) TABLE 1 Modulus Tension at Elongation MVTRModulus (F₁₀) Break at Break gm/m²/24 hr (Hand) (N/cm) (N/cm) (%)Upright MD CD MD CD MD CD MD CD Method Example 1 5 4 3.06 2.31 17.512.25 480 408 8900 Example 3 7 4 3.12 2.19 26.25 11.38 640 380 500Example 9 18 6 5.6 4.03 13.1 8.93 92 91 NA TEGADERM 2 2 0.46 0.46 4.734.38 360 340 4000 HP¹ OP-SITE IU² 1 1 0.72 0.72 9.98 9.45 545 555 1540¹TAGADERM ™ HP #9536HP, transparent dressing with label; 10 × 12 cm; Lot#2001-07 HD²OP-SITE ™ IV3000 moisture responsive cannula dressing; 10 × 14 cm; Lot#9243

As seen from Table 1, the presence of distinct phases in Example 3provided an adhesive article with significantly increased stiffness(higher Hand and F₁₀ Modulus values), significantly increased tensilestrength and a high degree of breathability (MVTR greater than 300gm/m²/24 hr) as compared to the two commercial adhesive dressings thatdo not contain phases.

All patents, patent documents, and publications cited herein areincorporated by reference. The foregoing detailed description andexamples have been given for clarity of understanding only. Nounnecessary limitations are to be understood therefrom. The invention isnot limited to the exact details shown and described, for variationsobvious to one skilled in the art will be included within the inventiondefined by the claims.

1. A conformable adhesive article for use as a sterile medical dressing,the article comprising: a substantially continuous breathable polymericmatrix comprising an elastic material, and having a first surface and asecond surface; a plurality of phases retained proximate the polymericmatrix, the plurality of phases substantially discontinuous in a firstdirection and substantially continuous in a second direction; and anadhesive composition positioned on at least a portion of the firstsurface of the polymeric matrix; wherein the plurality of phases areretained on the second surface of the polymer matrix.
 2. The conformableadhesive article according to claim 1, wherein the breathable polymericmatrix comprises at least a first layer and a second layer.
 3. Theconformable adhesive article according to claim 2, wherein the firstlayer and second layer comprise different compositions.
 4. Theconformable adhesive article according to claim 1, wherein the pluralityof phases comprise a substantially non-elastic material.
 5. Theconformable adhesive article according to claim 1, wherein the pluralityof phases are heat laminated between a polymeric matrix having at leasttwo layers.
 6. The conformable adhesive article according to claim 1,wherein the polymeric matrix is extruded in two stages.
 7. Theconformable adhesive article according to claim 1, wherein the polymericmatrix material is solvent cast onto a release sheet.
 8. The conformableadhesive article according to claim 1, wherein the article comprises aroll good.
 9. The conformable adhesive article according to claim 8,wherein the roll good is perforated to form individual lengths ofsterile medical dressings.
 10. A conformable adhesive article for use asa sterile medical dressing, the article comprising: a breathablepolymeric matrix having a first surface and a second surface; aplurality of phases proximate the polymeric matrix; and an adhesivecomposition positioned on at least a portion of the first surface of thepolymeric matrix; wherein the adhesive article has a conformability ofgreater than 2 and less than 10 in a direction parallel to the pluralityof phases.
 11. The conformable adhesive article according to claim 10,wherein the article has an inverted moisture vapor transmission rate ofat least about 1500 g/m²/24 hrs.
 12. The conformable adhesive articleaccording to claim 10, wherein the plurality of phases retainedproximate the polymeric matrix are retained within the polymeric matrix.13. The conformable adhesive article according to claim 10, wherein theplurality of phases substantially surrounded by the polymeric matrix areincompatible with the polymeric matrix.
 14. The conformable adhesivearticle according to claim 10, wherein the plurality of phases areretained on the second surface of the polymer matrix.
 15. Theconformable adhesive article according to claim 14, wherein theplurality of phases are retained intermediate the adhesive compositionand the first surface of the polymeric matrix.
 16. The conformableadhesive article according to claim 10 wherein the breathable polymericmatrix comprises an elastomeric material and the plurality of phasescomprise a substantially non-elastic material.
 17. A conformableadhesive roll good for use as a sterile medical dressing, the roll goodcomprising: a breathable polymeric matrix having a first surface and asecond surface; a plurality of substantially continuous phases retainedproximate the polymeric matrix; an adhesive composition positioned on atleast a portion of the first surface of the polymeric matrix.
 18. Theconformable adhesive roll good according to claim 17, wherein the rollgood comprises perforations to form individual lengths.
 19. Theconformable adhesive roll good according to claim 18, wherein theplurality of substantially continuous phases are discontinuous at theperforations.
 20. The conformable adhesive article according to claim17, wherein the article has an inverted moisture vapor transmission rateof at least 1,500 g/m²/24 hours.
 21. A conformable adhesive article foruse as a sterile medical dressing, the article comprising: asubstantially continuous breathable polymeric matrix comprising anelastic material, and having a first surface and a second surface; aplurality of phases retained proximate the polymeric matrix, theplurality of phases substantially discontinuous in a first direction andsubstantially continuous in a second direction; and an adhesivecomposition positioned on at least a portion of the first surface of thepolymeric matrix; and wherein the plurality of phases are retained onthe first surface of the polymeric matrix.
 22. The conformable adhesivearticle according to claim 21, wherein the plurality of phases areretained intermediate the adhesive composition and the first surface ofthe polymeric matrix.
 23. The conformable adhesive article according toclaim 21, wherein the breathable polymeric matrix comprises at least afirst layer and a second layer.
 24. The conformable adhesive articleaccording to claim 23, wherein the first layer and second layer comprisedifferent compositions.
 25. The conformable adhesive article accordingto claim 21, wherein the breathable polymeric matrix comprises anelastomeric material, and the plurality of phases comprise asubstantially non-elastic material.
 26. The conformable adhesive articleaccording to claim 21, wherein the breathable polymeric matrix and theplurality of phases comprise elastomeric materials.
 27. The conformableadhesive article according to claim 21, wherein the plurality of phasesare heat laminated between a polymeric matrix having at least twolayers.
 28. The conformable adhesive article according to claim 21,wherein the polymeric matrix is extruded in two stages.
 29. Theconformable adhesive article according to claim 21, wherein thepolymeric matrix material is solvent cast onto a release sheet.
 30. Theconformable adhesive article according to claim 21, wherein the articlecomprises a roll good.
 31. The conformable adhesive article according toclaim 30, wherein the roll good is perforated to form individual lengthsof sterile medical dressings.